Circuit breaker



Aug. 13, 1935. B. w. KERR CIRCUIT BREAKER Filed April 21, 1950 Patented Aug. 13, 1935 UNITED STATES PATENT OFFICE GIMUIT BBEAKIR Afllililfifll All! 21, 1930, Serial No. 446,131

11 Claims.

This invention relates to circuit breakers and particularly to circuit breakers adapted for use nth. circuits can-yin: relatively high voltages wmre quick oi. the breaker elements .2 is required.

One ofrthe ohiecmof. the invention is the provision of a circuit breaker in which the arc is conlinen. in a small space and the contact elements ate-separated so quickly that no destructive bumioringzcan occur.

Another obieutoflthe invention is the provision of a mechanically actuated high speed circuit breaha'in whichthe actuating means are inoperative and the circuit remains open as long as w 'the'couar to the circuit breaker casing is open.

Another object of my invention is the provision; 01a circuit breaker having removable actuating meansv which may be placed in position automatically by the closing of the cover to the 20. casing.

dither objects will be apparent from the following description when taken in camection with the appended drawing in. which:

Figs. 1 and 2 are vertical sections, taken subat right angles, tbrougha circuit breakor embodying the invention,

Figs. 3 and 4 are views of sections taken along line 3-; and line H in Fig. 2, respectively.

An elongated box-like casing l of porcelain or 3gother rugged insulating material having an open lower end is provided at its fnont side with a metallic door 2, hinged to the casing at its upper end and arranged to swing upwardly to permit access to the interior of the casing. The rear 35; wall 3 of the casing is-provided a forwardly oflset portion 4- extending longitudinally of the casing and sloping forwardly from the upper to the lower portion of the casim.

integral with, and onthe n'ont side of the oc- Q, set portion of the casing, is alongitudinally extending rib 5 having a cylindrical chamber 8 extending therethrough and open at both ends. Disposed across the upper end of the chamber is a terminal member I of conducting material & which member is secured to the casing by means of screws 8 disposed on diametrically opposite sides of the upper opening.

Inasmuch as screw threads can not be readily tamed in porcelain, it is necessary to provide iniifl: m I, of amaterial which can. be easily tapped. M the casing at. those points where it is desired screws in. the casing member.

clamped. between the terminal member I and the-integral rib 5,. and seeuredby means of the It: mwtwhiclrhoid theterminal member. is a pair of blade clips 9, the ends of which are bent into the cylindrical chamber to form a resilient socket. A conductor l0 may be secured to the terminal member from which conductor current may pass to the blade clips.

Secured to opposite sides of the opening at the lower end of the integral rib is a second pair of blade clips H which have their ends bent to form a socket similar to that formed by the first-mentioned pair but which extends away from the 10 chamber. Clamped between the lower blade clips and the integral rib is a guide member I2 having a perforation l3 extending therethrough and disposed coaxial with the axis of the cylindrical chamber.

Normally disposed in the cylindrical chamber is a blade comprising a conductive section adapted to span the gap between said pairs of clips, a handle for manually opening or closing the circuit breaken, and a portion adapted to be engaged by a projectile to open the circuit breaker in the case of an overload. The conducting section, indicated generally by reference numeral I4, has an enlarged tip i5 adapted to be gripped by the upper blade clips 9, a reduced shank l6 extending through the chamber and the socket formed by the lower blade clips II, and an enlarged lower end I1. The blade also includes a handle l8 of insulating material which extends from the lower end of the casing and a circular flange I9 disposed between the handle and the lower enlarged portion l1.

Secured to the front side of the lower end of the integral rib is a pair of fuse clips 20, 2| in which may be secured a cylindrical fuse 22 of the shot gun type (described more fully below), the axis of which, if prolonged, would intersect the disk IS. A third fuse clip 23, arranged to grip the fuse intermediate the first mentioned clips, is carried on the inner wall of the casing cover 2.

A lower terminal 24 is secured adjacent the upper fuse clip 2| and electrically connected therewith.

The first-mentioned fuse clips 20, 2| are of the usual type being merely strips of resilient metal bent in the shape of a U, as shown in detail in Fig. 4. The second type of fuse clip 23 comprises a pair of oppositely disposed resilient arms 25 carrying on their opposing faces. a pair of blocks 26 of insulating material having slightly arcuate sides arranged to fit around the fuse 22.

Formed integral with the cover of the casing is a stop member 21 having its lower surface perpendicular to the wall of the cover and arranged 55 to fit against the top end of the fuse when the latter is in its normal position in the clips.

The shot gun fuse 22 mentioned above comprises a cylindrical casing 28 of insulating material filled with an explosive charge 29 in which is embedded an ignition wire or fusible conductor 3o connecting the end terminals of the fuse. Disposed in the lower end of the fuse is a slug (not shown) of lead or similar heavy material. The explosive charge is ignited by' the heating of the wire 39 when an excessive current passes therethrough and the explosion causes the slug to be expelled from the fuse with a high velocity.

In operation the ends of the line in which the circuit breaker is to be connected are brought to the upper and lower terminal members respectively, by means of the terminal lugs.

The blade is pushed up until the enlarged ends 15, ll of the conductive section are engaged by the upper and lower socket, respectively, and the circuit thus completed between the upper and lower terminals.

The fuse is then inserted in the fuse clip which is carried by the cover and the cover is closed, thus bringing the fuse into engagement with the fuse clips carried by the casing to complete the circuit between the two ends of the line. The circuit may be traced as follows: from the upper terminal 1 through the upper blade clips 9 to the blade l4, through the blade 14 to the lower blade clips H, thence to the lower fuse clip 23; through the fuse 22 to the upper fuse clip 2| and to the lower terminal 24.

When an overload occurs, the heating of the fuse wire in the shot gun fuse ignites the charge and the slug is discharged from the fuse with high. velocity, the fuse casing being prevented from recoiling movement by the stop 21. The slug strikes against the circular flanged portion of the blade and effects downward movement of the latter to draw the tip and the lower enlarged portion of the blade from their respective sockets. The movement of the tip away from the upper socket thus breaks the circuit; the speed of separation of the members is such that arcing is substantially reduced or eliminated. Any tendency towards arcing will establish a pressure within the chamber and thus accelerate the movement of the blade.

The blade I4 is carried downwardly until the shoulder of the enlarged tip is engaged by the guide member l 2 which latter prevents the blade from leaving the casing.

The presence of the blade handle l8 extending out the bottom end of the casing serves as an indication that the circuit is open.

After an overload has caused the blade to be knocked down, the door may be opened and a new fuse placed in the clip carried by the door. While the door is open, the blade is replaced and then the door closed to complete the circuit. It will be seen that the circuit may be operated with complete safety as the circuit is never completed unless the door is closed. The circular shank is of such size as to prevent any attempt on the part of an attendant to insert his hand into the casing through the open lower end. Furthermore, the opening of the door will break the circuit at the fuse clips so that safety will be assured if the door is opened when the blade is in its uppermost position.

A vent is provided in the rear wall of the lower end of the chamber 6 for the escape of gases produced by the rupture of the circuit,

which gases might cause an explosion if no outlet were provided.

It should be apparent that it is not necessary to form the chamber walls integral with the casing as the chamber may well be constructed as a separate member secured inside of the casing member.

I claim:

1. A circuit opening device comprising a casing having a cover, a fixed contact member, a movable contact member, a projectile discharging fuse carried by said cover, a fuse holder disposed in said casing and arranged to receive said fuse when said cover is closed, said fuse being positioned to discharge its projectile against said movable contact member to separate the same from said fixed contact member.

2. In a circuit opening device, a casing member, a door for said casing member, two sets of blade clips in said casing member, a blade removably mounted in said clips and completing an electric circuit therebetween, a handle for said blade, a set of fuse clips on said casing member, and a powder-filled fuse secured on said door and having a projectile disposed therein, said fuse being positioned to enter said fuse clips when said door is closed.

3. The invention as set forth in claim 2 wherein said blade is provided with an enlarged tip and said casing is provided with means for engaging said tip to retain said blade in said casing when said circuit is opened.

4. In a circuit opening device, a casing member, a contact member therein, a vertically disposed movable blade cooperating with said contact member to close an electric circuit, means including a powder filled cartridge having a projectile normally spaced from said blade and arranged to strike against said blade for moving it downwardly away from said contact member and out of said casing, and means for retaining at least a portion of said blade in said casing after said blade has been moved away from said contact member.

5. In a circuit opening device, in combination, a pair of spaced, relatively stationary, contact clips, a movable contact element including a rigid member carrying a contact member at each end, said contact members being normally engaged in said stationary contact clips respectively, and means including an explosive fuse for moving said movable contact element to move both of said contact members out of engagement with their respective stationary contact clips.

6. In a circuit opening device, in combination, a pair of spaced and relatively stationary contact clips, a movable contact element including a rigid member and a pair of spaced contact members carried substantially at the ends thereof, said members normally engaging in said contact clips respectively, and means including an explosive fuse for actuating said movable contact element to thereby move said contact members outof engagement with their respective contact clips, said means being effective to impart to at leastv one of said contact members, movement substan tially along the axis of said rigid member during the initial portion of its movement.

'7. In a circuit opening device, a pair of contact members, a blade axially movable to bridge said contact members to close a circuit between the same, and means operable upon the passage of excess current through said circuit to move said blade axially to withdraw the same from one of said contact members, said means comprising a projectile normally spaced from and adapted to be projected approximately axially of and against said blade to move the latter axially into open position.

8. The invention as claimed in claim 7, wherein said blade has a flange projecting therefrom and arranged in the path of said projectile.

9. The invention as claimed in claim 7, in combination with a casing supporting said contact members and blade, said casing having an elongated chambered portion surrounding said blade when the latter is bridged across said contact members, said chambered portion constituting an arc-confining means.

10. In a circuit breaker, a casing member, a pair of contacts within said casing, a blade member adapted to move into and out of a position bridging across said contacts, an explosive i'use having a projectile normally spaced from said blade and arranged to strike said blade to open the circuit breaker, and a handle on said blade and extending to the exterior of the casing, whereby the condition of said circuit breaker is indicated exteriorly of said casing by said handie.

11. The invention as claimed in claim 10, wherein said blade is axially movable, and said casing includes an elongated vented tubular chamber portion enclosing one contact and said blade when the latter is in circuit-closing position, said chamber constituting an arc-confining means.

BENJAMIN W. KERR. 

